service.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <sys/types.h>
  15 #include <arpa/nameser.h>
  16 #include <sys/socket.h>
  17
  18 #include <resolv.h>
  19 #include <glob.h>
  20 #include <stdio.h>
  21 #include <time.h>
  22
  23 #include <libubus.h>
  24 #include <libubox/vlist.h>
  25 #include <libubox/uloop.h>
  26 #include <libubox/avl-cmp.h>
  27 #include <libubox/blobmsg_json.h>
  28
  29 #include "ubus.h"
  30 #include "dns.h"
  31 #include "service.h"
  32 #include "util.h"
  33 #include "interface.h"
  34 #include "announce.h"
  35
  36 enum {
  37         SERVICE_INSTANCE,
  38         SERVICE_SERVICE,
  39         SERVICE_PORT,
  40         SERVICE_TXT,
  41         __SERVICE_MAX,
  42 };
  43
  44 struct service {
  45         struct vlist_node node;
  46
  47         time_t t;
  48
  49         const char *id;
  50         const char *instance;
  51         const char *service;
  52         const uint8_t *txt;
  53         int txt_len;
  54         int port;
  55         int active;
  56 };
  57
  58 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
  59         [SERVICE_INSTANCE] = { .name = "instance", .type = BLOBMSG_TYPE_STRING },
  60         [SERVICE_SERVICE] = { .name = "service", .type = BLOBMSG_TYPE_STRING },
  61         [SERVICE_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
  62         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
  63 };
  64
  65 static void
  66 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
  67                struct vlist_node *node_old);
  68
  69 static struct blob_buf b;
  70 static VLIST_TREE(services, avl_strcmp, service_update, false, false);
  71 static int service_init_announce;
  72
  73 /**
  74  * service_instance_name - construct Service Instance Name as in RFC 6763
  75  *
  76  * RFC 6763 specifies Service Instance Names in the following way:
  77  *
  78  * Service Instance Name = <Instance> . <Service> . <Domain>
  79  *
  80  * @s: service to generate service instance name for
  81  */
  82 static const char *
  83 service_instance_name(struct service *s)
  84 {
  85         static char buffer[256];
  86
  87         snprintf(buffer, sizeof(buffer), "%s.%s", s->instance, s->service);
  88
  89         return buffer;
  90 }
  91
  92 static void
  93 service_add_ptr(const char *host, int ttl)
  94 {
  95         int len = dn_comp(host, mdns_buf, sizeof(mdns_buf), NULL, NULL);
  96
  97         if (len < 1)
  98                 return;
  99
 100         dns_add_answer(TYPE_PTR, mdns_buf, len, ttl);
 101 }
 102
 103 static void
 104 service_add_srv(struct service *s, int ttl)
 105 {
 106         struct dns_srv_data *sd = (struct dns_srv_data *) mdns_buf;
 107         int len = sizeof(*sd);
 108
 109         len += dn_comp(mdns_hostname_local, mdns_buf + len, sizeof(mdns_buf) - len, NULL, NULL);
 110         if (len <= sizeof(*sd))
 111                 return;
 112
 113         sd->port = cpu_to_be16(s->port);
 114         dns_add_answer(TYPE_SRV, mdns_buf, len, ttl);
 115 }
 116
 117 #define TOUT_LOOKUP     60
 118
 119 static time_t
 120 service_timeout(struct service *s)
 121 {
 122         time_t t = monotonic_time();
 123
 124         if (t - s->t <= TOUT_LOOKUP)
 125                 return 0;
 126
 127         return t;
 128 }
 129
 130 static void
 131 service_reply_single(struct interface *iface, struct sockaddr *to, struct service *s, int ttl, int force)
 132 {
 133         const char *host = service_instance_name(s);
 134         char *service = strstr(host, "._");
 135         time_t t = service_timeout(s);
 136
 137
 138         if (!force && (!s->active || !service || !t))
 139                 return;
 140
 141         service++;
 142
 143         s->t = t;
 144
 145         dns_init_answer();
 146         service_add_ptr(service_instance_name(s), ttl);
 147         dns_send_answer(iface, to, service);
 148
 149         dns_init_answer();
 150         service_add_srv(s, ttl);
 151         if (s->txt && s->txt_len)
 152                 dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len, ttl);
 153         dns_send_answer(iface, to, host);
 154 }
 155
 156 void
 157 service_reply(struct interface *iface, struct sockaddr *to, const char *instance, const char *service_domain, int ttl)
 158 {
 159         struct service *s;
 160
 161         vlist_for_each_element(&services, s, node) {
 162                 if (instance && strcmp(s->instance, instance))
 163                         continue;
 164                 if (service_domain && strcmp(s->service, service_domain))
 165                         continue;
 166                 service_reply_single(iface, to, s, ttl, 0);
 167         }
 168 }
 169
 170 void
 171 service_announce_services(struct interface *iface, struct sockaddr *to, int ttl)
 172 {
 173         struct service *s;
 174
 175         vlist_for_each_element(&services, s, node) {
 176                 s->t = 0;
 177                 if (ttl) {
 178                         dns_init_answer();
 179                         service_add_ptr(s->service, ttl);
 180                         dns_send_answer(iface, to, C_DNS_SD);
 181                 }
 182                 service_reply_single(iface, to, s, ttl, 0);
 183         }
 184 }
 185
 186 static void
 187 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 188                struct vlist_node *node_old)
 189 {
 190         struct interface *iface;
 191         struct service *s;
 192
 193         if (!node_old) {
 194                 s = container_of(node_new, struct service, node);
 195                 if (service_init_announce)
 196                         vlist_for_each_element(&interfaces, iface, node) {
 197                                 s->t = 0;
 198                                 service_reply_single(iface, NULL, s, announce_ttl, 1);
 199                         }
 200                 return;
 201         }
 202
 203         s = container_of(node_old, struct service, node);
 204         if (!node_new && service_init_announce)
 205                 vlist_for_each_element(&interfaces, iface, node)
 206                         service_reply_single(iface, NULL, s, 0, 1);
 207         free(s);
 208 }
 209
 210 static void
 211 service_load_blob(struct blob_attr *b)
 212 {
 213         struct blob_attr *txt, *_tb[__SERVICE_MAX];
 214         struct service *s;
 215         char *d_instance, *d_service, *d_id;
 216         uint8_t *d_txt;
 217         int rem2;
 218         int txt_len = 0;
 219
 220         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 221                 _tb, blobmsg_data(b), blobmsg_data_len(b));
 222         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_SERVICE])
 223                 return;
 224
 225         if (_tb[SERVICE_TXT])
 226                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 227                         txt_len += 1 + strlen(blobmsg_get_string(txt));
 228
 229         s = calloc_a(sizeof(*s),
 230                 &d_id, strlen(blobmsg_name(b)) + 1,
 231                 &d_instance, _tb[SERVICE_INSTANCE] ? strlen(blobmsg_get_string(_tb[SERVICE_INSTANCE])) + 1 : 0,
 232                 &d_service, strlen(blobmsg_get_string(_tb[SERVICE_SERVICE])) + 1,
 233                 &d_txt, txt_len);
 234         if (!s)
 235                 return;
 236
 237         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 238         s->id = strcpy(d_id, blobmsg_name(b));
 239         if (_tb[SERVICE_INSTANCE])
 240                 s->instance = strcpy(d_instance, blobmsg_get_string(_tb[SERVICE_INSTANCE]));
 241         else
 242                 s->instance = umdns_host_label;
 243         s->service = strcpy(d_service, blobmsg_get_string(_tb[SERVICE_SERVICE]));
 244         s->active = 1;
 245         s->t = 0;
 246         s->txt_len = txt_len;
 247         s->txt = d_txt;
 248
 249         if (_tb[SERVICE_TXT])
 250                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 251                         int len = strlen(blobmsg_get_string(txt));
 252                         if (!len)
 253                                 return;
 254                         if (len > 0xff)
 255                                 len = 0xff;
 256                         *d_txt = len;
 257                         d_txt++;
 258                         memcpy(d_txt, blobmsg_get_string(txt), len);
 259                         d_txt += len;
 260                 }
 261
 262         vlist_add(&services, &s->node, s->id);
 263 }
 264
 265 static void
 266 service_load(char *path)
 267 {
 268         struct blob_attr *cur;
 269         glob_t gl;
 270         int i, rem;
 271
 272         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 273                 return;
 274
 275         for (i = 0; i < gl.gl_pathc; i++) {
 276                 blob_buf_init(&b, 0);
 277                 if (blobmsg_add_json_from_file(&b, gl.gl_pathv[i])) {
 278                         blob_for_each_attr(cur, b.head, rem)
 279                                 service_load_blob(cur);
 280                 } else {
 281                         fprintf(stderr, "Error reading %s JSON\n", gl.gl_pathv[i]);
 282                 }
 283         }
 284         globfree(&gl);
 285 }
 286
 287 static void
 288 service_init_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 289 {
 290         struct blob_attr *cur;
 291         int rem;
 292
 293         get_hostname();
 294
 295         vlist_update(&services);
 296         service_load("/etc/umdns/*");
 297
 298         blob_for_each_attr(cur, msg, rem) {
 299                 struct blob_attr *cur2;
 300                 int rem2;
 301
 302                 blobmsg_for_each_attr(cur2, cur, rem2) {
 303                         struct blob_attr *cur3;
 304                         int rem3;
 305
 306                         if (strcmp(blobmsg_name(cur2), "instances"))
 307                                 continue;
 308
 309                         blobmsg_for_each_attr(cur3, cur2, rem3) {
 310                                 struct blob_attr *cur4;
 311                                 int rem4;
 312                                 int running = 0;
 313
 314                                 blobmsg_for_each_attr(cur4, cur3, rem4) {
 315                                         const char *name = blobmsg_name(cur4);
 316
 317                                         if (!strcmp(name, "running")) {
 318                                                 running = blobmsg_get_bool(cur4);
 319                                         } else if (running && !strcmp(name, "data")) {
 320                                                 struct blob_attr *cur5;
 321                                                 int rem5;
 322
 323                                                 blobmsg_for_each_attr(cur5, cur4, rem5) {
 324                                                         struct blob_attr *cur6;
 325                                                         int rem6;
 326
 327                                                         if (strcmp(blobmsg_name(cur5), "mdns"))
 328                                                                 continue;
 329
 330                                                         blobmsg_for_each_attr(cur6, cur5, rem6)
 331                                                                 service_load_blob(cur6);
 332                                                 }
 333                                                 break;
 334                                         }
 335                                 }
 336                         }
 337                 }
 338         }
 339         vlist_flush(&services);
 340 }
 341
 342 void
 343 service_init(int announce)
 344 {
 345         get_hostname();
 346
 347         service_init_announce = announce;
 348         ubus_service_list(service_init_cb);
 349 }
 350
 351 void
 352 service_cleanup(void)
 353 {
 354         vlist_flush(&services);
 355         blob_buf_free(&b);
 356 }